FIG. 1 depicts a side view of portion of a conventional energy assisted magnetic recording (EAMR) disk drive 10. For clarity, FIG. 1 is not to scale. For simplicity not all portions of the EAMR disk drive 10 are shown. The EAMR disk drive 10 includes an EAMR head 11 including a slider 12 and a transducer 20. THE EAMR disk drive 10 also includes a laser/light source 14, media 18, a transducer 20, and preamplifier and associated circuitry 30. The laser 14 is typically a laser diode. Although shown as mounted on the slider 11, the laser 14 may be coupled with the slider 11 in another fashion. For example, the laser 11 might be mounted on a suspension (not shown in FIG. 1) to which the slider 11 is also attached. The media 18 may include multiple layers, which are not shown in FIG. 1 for simplicity.
The EAMR head 11 includes an EAMR transducer 20. The EAMR head 11 may also include a read transducer (not shown in FIG. 1). The read transducer may be included if the EAMR head 11 is a merged head. The EAMR transducer 20 includes optical components (not shown in FIG. 1) as well as magnetic components (not shown in FIG. 1).
Also shown in conventional pre-amplifier 30. As shown in FIG. 1, the pre-amplifier 30 is typically located remote from the slider 12. For example, the pre-amplifier may reside on a flexible printed circuit board (actuator flex). The actuator flex provides mechanical and electrical connection between a system on a chip (SOC) including other electronics and the slider 12, which is typically mounted on the actuator flex. The conventional pre-amplifier 30 typically provides DC power for the conventional laser diode 14 and power for the transducer 20. For the transducer 20, the pre-amplifier 30 may be connected by two lines for a fly height sensor that helps determine the distance between the ABS and the media, one to two lines for a fly height control heater and ground, two lines for read data, and two lines for the write data.
In operation, the pre-amplifier 30 provides a constant power signal to the laser 14 during writing. Thus, the laser 14 remains on throughout the write operations. The laser 14 provides a constant source of energy, which is used to heat small regions of the media 18. The pre-amplifier 30 also provides write signals to the transducer 20. The write signals selectively energize one or more coils (not shown in FIG. 1). These coils energize a write pole (not shown in FIG. 1). The transducer 20 then magnetically writes to the media 18 in the heated region.
Although the conventional EAMR disk drive 10 functions, it is desirable to reduce power consumption of the EAMR disk drive 10. For example, a conventional near-field transducer (NFT) (not shown) is typically used to focus light from the conventional laser 14 onto the media 18. However, the conventional NFT is subject to overheating during use. The NFT may thus deform, melt, or corrode. Further, the lateral thermal gradient in the media 18 may be lower than desired. Stated differently, the temperature of the media 18 does not fall off sufficiently quickly in the cross track direction from the region being heated. Thus, the track widths recorded by the conventional EAMR transducer 20 may be wider than desired. Consequently, a mechanism for controlling the power consumed by the conventional EAMR disk drive 10 is desired.
Accordingly, what are needed are improved methods and systems for controlling power consumption in EAMR disk drives.